1. Field of the Invention
The present invention pertains to trailers. More particularly, the present invention pertains to means for varying the height of trailer walls and the trailers obtained thereby. Even more particularly, the present invention pertains to trailers having vertically extensible and retractable walls.
2. Prior Art
As is known to those skilled in the art to which the invention pertains, tractor-trailer assembles have been provided with innovations and accoutrements, designed to facilitate the transfer of a load. However, little attention has been paid to the driving of the assembly when the trailer is either unloaded or only partly loaded.
Present day trailers, generally, have standard size frames with fixed height sidewalls. This inherently creates problems. For example, when loaded to less than capacity, there is created the problem of shifting packages and cartons. This, in turn, leads to breakage and damage and the concomittant loss in dollars. Another problem encountered is more directed to the structure, per se. Because of the fixed height of the walls of the trailer, the driver must rely solely upon side view mirrors for rear viewing. This, of course, creates a serious disadvantage to the driver. Furthermore, this reliance solely on side mirrors is present regardless of the presence or absence of a load in the trailer.
Furthermore, the air resistance about the trailer is constant due to the fixed height trailer walls. By being able to shorten the height of the walls and, therefore, the area thereof the resistance to air is reduced thereby giving somewhat increased fuel mileage.
For all of these reasons, a benefit to the art would be provided by a trailer having extensible and retractable sidewalls. It is to this to which the present invention is directed.